1. Field of the Invention
The present invention relates to a scorotron charging apparatus consisting of a wire, shield, and a grid used in an electrophotographic apparatus including a printer and a copying apparatus and in particular, to a scorotron charging apparatus including a side seal arranged between the grid and the shield.
2. Description of the Related Art
It is known that in a conventional scorotron charging apparatus in an electrophotographic apparatus, charging can be performed with less wire current by increasing the shield voltage.
As shown in FIG. 7, the conventional scorotron charging apparatus is an electric charger including a shield 31, a grid 33, and a wire 34. In this electric charger, the voltage of the shield 31 is increased to obtain a potential between the grid 33 and the wire 34 while a sufficient interval xe2x80x9caxe2x80x9d is required between the shield 31 and the grid 33 so that no arc discharge is caused. For this, ozone leaks through the interval xe2x80x9caxe2x80x9d in this electric charger.
Moreover, as shown in FIG. 8, another type of conventional scorotron apparatus includes a shield 41, a grid 43, a wire 44, and an insulation material 42 covering the space between the shield 41 and the grid 43, so that no ark discharge is caused between the shield 41 and the grid 43 and leakage of ozone can be prevented. In the space inside this electric charger, a great amount of ion in generated. In this structure, the ion adheres to the insulation material 42 to cause charging. Moreover, when the charging potential of the insulation material 42 exceeds a predetermined value, arc discharge is caused with respect to the shield 41 and the grid 43, causing an incorrect operation of a control circuit in the vicinity due to noise.
It is therefore an object of the present invention to provide scorotron charging apparatus including a side seal made from a semiconductor material arranged between the grid and shield so as to increase the charging efficiency and assure a uniform and stable charging.
The scorotron charging apparatus according to the present invention comprises: a wire; a shield; a grid; and a side seal arranged between the grid and the shield.
According to another aspect of the present invention, the side seal may be made from a semiconductor material.
According to still another aspect of the present invention, the side seal may have a resistance value in a range from 1 to 100 Mxcexa9.
According to yet another aspect of the present invention, the side seal may be made from a conductive plastic containing a conductive agent such as carbon.
According to still further aspect of the present invention, the conductive plastic may be polycarbonate or polyacetal containing a conductive agent such as carbon.
According to yet still another aspect of the present invention, the side seal may be made from a material having a resistance value in a range from 1M to 1000 Mxcexa9 cm.
According to still yet another aspect of the present invention, the current flowing into the side seal may create a voltage inclination.
According to yet another aspect of the present invention, the side seal may be made from a flat plate.
According to still another aspect of the present invention, a plurality of holes may be opened in the back surface of the shield for exhausting air.
According to still yet another aspect of the present invention, the apparatus may further comprise a fan arranged for generating an air flow through the plurality of holes for exhausting air.